buy a pc?

it's not a question really, i already decided to buy a pc for racing sims and games.
but i have no clue which specifications i need and how much money a have to spend.
what's important? GraKa, memory, processor?
i am also going to buy a multi monitor set. (3 monitors)

Core i5 is good, i7 is overkill and not required. You can use the money saved to buy a better graphics card. If you want to save some cash, Get the AMD Phenom II X4 955 CPU with 4Gb ram and at least a 6850 ATI card. This will give you plenty of power and allow you to run triple monitors. If you want a complete list of parts, let me know and I will come up with the specs that will work great for you. Also, let me know the amount of money you don't want to spend more than so I can figure that into the parts I find for you.

@ Jim Cole
i am not sure if i should by the parts and build it together myself or by a complete pc.
TBH i have to do some rendering on the pc for my job too but i want to play sims and games also.
i want to check out rfactor! and f1 2011 with aaaaaaaaallll the mods
and this should work as long as possible.
i worked until now with an apple computer so i have no idea how much money i should spend.
about 700-800 euros i think. is this enough?
if you could send me a list with all the parts i need that would be great!
thank you very much!

SSD's are used by most folks for the boot drive only. It is possible to use it for image storage, but that isn't really important as when you are doing rendering, you want the image loaded into ram instead of bring it from the hard drive during the render process. I would suggest making sure you are running a 64bit version of the operating system and getting at least 16Gb ram in the system to help with the rendering. Also, if you are planning on doing rendering I would further suggest that you get an i7 instead of the i5 as the performance boost for renders will be very noticable. The upgrade to the i7 shouldn't be more than about another $100 to $150 US dollars and would work with the same motherboard that was mentioned by ProSimEU.

I agree with the i5 2500K, I like being able to over clock things
I would use any board that can use atleast 2X SLI, my preferred brand being MSI for Mobo. No one says you have to use SLI right away, but I like having the option to easily upgrade rather than having to buy a new system. I have never been a fan of Radeon so I have no idea if they're faster right now than nVidia but I like sticking to my beliefs
Some Corsair 1600Mhz ram and I think 8 - 16gb is more than enough
I would get 2 EVGA GTX 560's, there 2gb each
I would also not care in the slightest about the HD, personnally I'd get like a 60gb because I'd load too much crap onto it if I ha anything bigger, I already have 4TB worth of external drives. My brother in law works in robotics and he's used a SSD for a few years, but I don't think I would personally benifit from it. Other than the insanely quick loading times for anything and everything being a plus.
Don't overlook the power supply Wattage.
This is all based on personal opinion but this is going to be my new setup when rFactor 2 comes out. Get to join the elite triple monitor people and I'm excited. Plus the pc should be able to run insane numbers and have a long life of high graphic gaming.

Just a note about the system bit rate. Win 7 32 bit doesn't support more than 4gb of ram, it can be in there but it won't use any of it. 64 bit can run whatever you want really. Here's a nice list for you